Beckhoff KL4424 K-Bus 4-Channel Analog Output Terminal

Description

Generating precise analog control signals within the Beckhoff I/O framework, the Beckhoff KL4424 operates as a high-density, four-channel current output module. Engineered to process signals in the standard 4 to 20 mA range, this terminal delivers high resolution and galvanic isolation to field-level actuators, control valves, and current-loop indicators. Its robust design is optimized for environments demanding dependable noise immunity and stable performance under fluctuating thermal conditions.

Key Features

• Four Single-Ended Channels: Compact integration of four analog outputs within a single 12 mm Bus Terminal housing.
• 12-Bit Resolution: High-precision digital-to-analog conversion providing precise process control execution.
• Short-Circuit Proof: Outputs are protected against wiring faults and load fluctuations up to 350 Ohms.
• Flexible Power Options: Operates natively via 24 V DC power contacts, with support for 15 V DC via the KL9515 power supply terminal.
• Galvanic Isolation: Provides 500 V isolation between the internal K-bus electronics and the signal channels.
• Comprehensive Certifications: Approved for hazardous areas with ATEX, IECEx, and cFMus Class I Division 2 ratings.

Applications

• Modulating valve positioners and pneumatic actuators in oil and gas refineries.
• Variable frequency drive speed reference control over standardized current loops.
• Process instrumentation control in chemical processing plants.
• Water and wastewater flow rate configuration systems.

Technical Specifications

Connections and Interfaces

Alternative Models & Compatibility

The terminal utilizes standard K-bus backplane communication and can be combined seamlessly with other standard bus terminals. For installations requiring pluggable wiring harnesses to minimize field maintenance times, the KS4424 version serves as the direct hardware equivalent featuring pluggable connector blocks.

Application Pitfalls & Engineering Notes

When sizing current loops, ensure that the total loop resistance does not exceed 350 Ohms. Exceeding this limit will cause the output driver to saturate before reaching the full 20 mA signal level, resulting in non-linear control. In high-density cabinet layouts with elevated ambient operating temperatures, consider powering the terminal at 15 V DC using a KL9515 terminal block to minimize local thermal dissipation within the enclosure.

Commissioning & Wiring Tips

To protect sensitive low-level analog signals from electromagnetic interference, use shielded twisted-pair (STP) cabling for all output runs. Ground the cable shield only at the entry point of the control cabinet to avoid forming ground loops. Ensure that the 0 V reference terminals (5 through 8) are properly bridged to the common power contact ground path to prevent common-mode voltage offsets on the analog signals.

Installation Guidelines

Snap the module onto a standard 35 mm DIN rail (EN 60715), ensuring that the locking mechanism engages securely with the rail's edges.

Slide the terminal horizontally along the DIN rail to interconnect the K-bus and power contacts with adjacent terminals. Verify that the side tongue-and-groove joints are fully locked.

Insert wire connections using a screwdriver to open the spring-loaded tension clamps. Ensure only stripped conductors without frayed copper strands are inserted, then release the spring clamp to lock the connection.